The sound production principle of a speaker is the following. When an electric current passes through a wire coil, the wire coil generates a magnetic pole, and then the wire coil and a magnet repel or attract by their own poles. The repelling or attraction can lead to inward shrinkage or outward expansion of an acoustic diaphragm so as to form gas flow. Finally, the sound is produced by the formation of gas flow.
The material of the acoustic diaphragm is a factor for determining the sound quality. The currently-used acoustic diaphragm is made by forming a coating on a substrate. The material of the substrate is metal, plastic, fabric, or paper; the material of the coating is metal (e.g. nickel, gold, silver, copper, chromium, titanium, aluminum, iron, indium, zirconium, germanium, tantalum, tungsten, or beryllium), alloy (e.g. nickel-iron alloy, titanium-magnesium alloy, silver-tin alloy, beryllium alloy, titanium alloy, or boron alloy), oxide (e.g. aluminum oxide, titanium oxide, magnesium oxide, tantalum oxide, indium tin oxide, or silicon dioxide), diamond, carbon, boron, diamond-like carbon, carbide, boride, or nitride. See Taiwan Utility Patent No. M358503, Taiwan Utility Patent No. M498432, Taiwan Invention Patent No. I539836, China Utility Patent No. CN201758445U, China Utility Patent No. CN204291352U, China Utility Patent No. CN87215838U, China Invention Patent No. CN1925696B, China Invention Patent No. CN100397953C, China Invention Patent No. CN1303848C, China Invention Publication No. CN104562140A, American Utility Patent No. U.S. Pat. No. 4,135,601, American Utility Patent No. U.S. Pat. No. 7,529,382, American Utility Patent No. U.S. Pat. No. 4,470,479, American Utility Patent No. U.S. Pat. No. 5,241,140, and American Utility Patent No. U.S. Pat. No. 7,539,324.
As described above, there are various materials of the acoustic diaphragm. However, the user is more and more fastidious about the sound quality of a speaker, and therefore it is desirable to develop another acoustic diaphragm to satisfy the user's hearing needs.